CRYSTAL-STRUCTURE OF 2 RETRO-INVERSO SWEETENERS

We have solved the structure of a crystal composed of two diastereomers, N-L-aspartyl-N′-[(2,2,5,5-tetramclhylcyclopentanyl)carbonyl]-(R)-1,1-diaminoethane (L, R isomer) and N-L-aspartyl-N′-[(2,2,5,5-tetramethylcyclopentanyl)carbonyl]-(S)-1,1-diaminoethane (L, S isomer). Both diastereomers are intensely sweet and are retro-inverso stereoisomers of dipeptides. We have related the crystal structure of these molecules to our model to explain the sweetness of pcptidc-bascd ligands. The “L shape” postulated on the basis of molecular mechanics and NMR spectroscopy is in full agreement with the crystal structures. © 1990, American Chemical Society. All rights reserved.